A ball-grid-array printed-circuit-board assembly includes a die, a plurality of solder-balls, a substrate, a top-metal layer, and a bottom-metal layer. The die includes a signal-out-pad and a plurality of ground-pads arranged about the signal-out-pad. The top-metal layer, a plurality of vias in the substrate, and the bottom-metal layer cooperate to form a substrate-integrated-waveguide. The top-metal layer is configured to define a U-shaped-slot between a signal-portion of the top-metal layer aligned with the signal-out-pad and the substrate-integrated-waveguide, and a ground-portion of the top-metal layer aligned with the plurality of ground-pads. The U-shaped-slot is characterized by a slot-length that is selected based on the frequency of a signal, and a slot-width that is selected based on the via-height such that the signal generates an electric field directed across the U-shaped-slot whereby the signal is propagated from the signal-portion of the top-metal layer into the substrate-integrated-waveguide.